Fluid pressure motor construction



Feb. 13, 1968 c. N. FRENCH ETAL 3,368,459

FLUID PRESSURE MOTOR CONSTRUCTION Filed Oct. 17, 1966 INVENI6R5 CHARLIEN. FRENCH ROBERT R. HAGER THoMAs M- BY rromlsw United States Patent3,368,459 FLUID PRESSURE MOTOR CONSTRUCTION Charlie N. French, Robert R.Hager, and Thomas M.

Julow, South Bend, Ind., assignors to The Bendix Corporation, acorporation of Delaware Continuation of application Ser. No. 400,503,Sept. 30, 1964. This application Oct. 17, 1966, Ser. No. 587,348 18Claims. (Cl. 91-391) ABSTRACT 0F THE DISCLOSURE A fiuid pressureservomotor having means operatively connected to a movable walltherewithin to render its power assistance capability progressivelyweaker after a predetermined stroking of said wall with additionalmeans, if desired, to limit travel of a manual control for theservomotor until power assistance is weakened or eliminated whereuponthe limiting means is released to permit the necessary travel of themanual control.

The present invention relates to fluid pressure motors having at leasttwo diaphragms or seals with respect to the servomotor housing; and moreparticularly to fluid pressure servornotors of the type having a pair ofpower diaphragms which move together, and a means for indicating theapproach of the maximum permissible movement for said power diaphragrns.This application is a continuation of our parent application Serial No.400,503 filed September 30, 1964, now abandoned.

In devices such as power brake servomotors and the like, it has becomeincreasingly desirous to obtain little or no travel for the operationthereof. This has in many instances provided a driver of a vehicle witha false sense of security as to the condition of the vehicle brakes. Forexample, until the servomotor has reached the stroke runout conditionwhere the movable wall therein has traveled a maximum amount, therewould not be any excessive travel sensation imparted to the driver of aneed for brake lining adjustments and the like. It is therefore aprincipal object of this invention to provide a means for indicating theapproach of excessive travel within a servomotor of the type mentioned,prior to the actual occurrence of the stroke run-out condition.

It is another object of this invention to provide a new and improvedarrangement for sealing a plurality of diaphragms within an internalhousing of a fluid pressure motor of an interchangeable nature which arearranged to operate independently of each other.

It is a further object of this invention to provide a unit of theaforesaid type with a balanced valve having a large area to eliminateunnecessary valve forces operative with incremental movements to permitlarge flow volumes. Smaller valves are known to require to /2 inch oftravel; whereas with a valve of this type we have reduced this travel toto inch without adding to the forces needed to operate the valve.

It is a still further object of this invention to provide a releasableholding means for the aforesaid valve means which will permit thetranslation of the whole valve means upon the release thereof, as duringa manual follow-through application under heavy operator loading.

It is also a further object of our invention to provide a springretention means for the aforesaid valve means to simplify constructiontechniques.

It is a more specific object of our invention to utilize a series ofhigh-rate springs which are arranged to become operative as one of thewalls reaches approximately twothirds of its maximum travel so thatforce required to provide further stroke for the wall thereafter willincrease by a much greater proportion to provide a heavy feel to3,368,459 Patented Feb. 13, 1968 the operator of the servomotor, therebyindicating a need for inspection of the system operated thereby.

Other and further objects will appear from the following description ofthe drawing showing a cross sectional view of a servomotor designed inaccordance with the principles of our invention.

With more particular regard to the figure, we show a servomotor 10formed from the forward and rearward shell 12 and 14, respectively,joined as at 16 by a method more particularly described in US. PatentNo. 3,146,682 assigned to the common assignee. As seen, the forwardshell 12 is provided with a fluid connection 18 that is to be connectedwith a sub-atmospheric source, such as an engine intake manifold.Furthermore, the shell 12 is also provided with a conduit 23 thatconnects with the fitting 18 that in turn connects with another conduit22 to communicate the rear shell 14' with the same sub-atmosphericsource. The fitting 18 is designed to be sealingly connected to astamped opening in the forward shell 12 intermediate its ends, as shown.

Upon joining the shells 12 and 14 and we utilize a plastic spacer body24 to position sealing beads 26, 28 and 30 of a forward diaphragm 32, anintermediate diaphragm 3d and a rear diaphragm 36, respectively, betweena shoulder 38 formed in the forward shell 12 and a radial flange 40 inthe rear shell 14-.

The forward diaphragm and intermediate diaphragm are also sealinglyconnected with movable walls 42 and 44 made from the same die to allowuniversal use prior to assembly. The walls, when assembled in the shellsl2 and 14, create a front variable volume chamber 46 and an intermediatevariable volume chamber 48. The rear diaphragm 36 is joined with aplate-like structure having a forward section 50 and a rearwardlyprojecting portion 52 to further divide variable volume chambers 54 and56 from the remaining portion of the servomotor behind the movable wall44.

The movable walls are formed such that a forward annular plate 58 and acentral tubular projection 66 can be afiixed thereto, as on the frontface of the movable wall 44- to abut the rear face of the movable wall42, thereby providing a compression link between the aforesaid movablewalls. More particularly, the plate 58 can be set on the tube 60 whichis sealingly connected to wall 44 as by resistance welding. This insuresthe integrity of chambers 54 and 48 and allows plate 58 to move withinchamber 48, with or relative to, wall 44. The plate 58 is stamped toform a plurality of leaf springs 62 peripherally so as to cooperate withthe inwardly extending portions of the spacer 24 as will be describedfurther hereinafter. It should also be noted at this time, however, thatthe inwardly directed portion of the spacer terminates in a seal 64which cooperates with the tubular projection 60 to separate the variablevolume chamber 43 from a still further variable volume chamber 66 whichis communicated internally of tube 60 to the variable volume chamber 54.Wall 44 can be drilled as at 67, or preformed with a larger hole toprovide an adequate fiow passage. As seen, the variable volume chamber66 is communicated internally of the tubular projection 60 by means ofthe space 67 between the movable wall 44 and a force transmitting rod 68maintained by the bearing and seal contact of the spacer 24 andprojection 60. A shoulder 70 of rod 68 is resistance welded to theforward movable wall 42 to provide force transmission contact therewith;and the tubular projection 60 is punched or drilled at spaced intervalsto provide radial openings 72 to permit the aforesaid flowcommunication. As with other units of the same general type as we haveherein shown, we provide a seal 74 adjacent the opening in the forwardshell 12 surrounding the force transmitting rod 68. However, 'we havemodified this opening somewhat by inserting therein a hat-shaped member76 which cooperates with a C-Washer 7 8 fitted in a groove in member 68to provide a rear stop for the force transmitting member. This does awaywith the need of an adjustable push rod or force transmitting rod 68 inthat a spring 69 will maintain the rearward position of the push rodconstant from unit to unit regardless of the positions of the internalstructure.

As seen, the spacer 24 is provided with a radially disposed opening topermit communication of fluid pressure from the fitting 18 to within thechamber 48.

As for the rear diaphragm 36 and the two portion movable walls to whichit is attached inwardly of the rear shell 14, we have shown a means ofbiasing a valve assembly between the forward portion 50 and the rearwardprojection 52 before assembling of these projections as by bolts 82.More particularly, we have shown a valve carrying body 84 and aconcentric surrounding valve seat member 86 which are biased by means ofsprings 88 and 90, respectively, towards the rear of the shell 14. Thepoppet body 84 is shown in its rearward position abutting a plurality ofribs formed on member 86 through valve seat 104 and annular seat 112.The body 84 is connected with a link 92 as by the member 94 which is inturn connected with a pedal operating member 96. The seat carryingmember 86 is constructed to radially abut upon a downward turned flange98 of the rear portion 52 due to the biasing action of the spring 90between the member 86 and a spacer member 100 that abuts the forwardportion 50.

As seen, the central body 84 is connected to the spacer 108 by means ofan annular diaphragm 182 and the valve seat carrying member is connectedto the valve seat 104 by means of another diaphragm 106 at the oppositeend of the central core 84. In the position shown, the valve poppetcarrying member bearing a pair of resilient rings 108 and 110 ispositioned in its forwardmost attitude on the central body 84 to abutthe annular seat 112 formed on the central body and to be spaced from adepending seat 114 of the seat carrying member 86. In such a position,the pressure in the tube 22 enters through an opening 116 in therearward projection 52 to a radical opening drilled in the seat carryingstructure 86, as at 118, at spaced intervals therearound to pass aboutthe poppet rings 108 and 110 into the chamber 54 as by an opening 120 inthe forward portion 50. Pressure differing from that in tube 22 andchamber 56 is introduced to the opposite sides of diaphragms 102 and 106through a central opening 122 and a passage 124 formed in the member 84so that the seal rings 108 and 110 will be positioned as shown. In theevent the pedal 96 is moved inwardly toward the servomotor 10, the seat112 will be displaced from the ring 108 and the ring 110 will be causedto bear upon the depending seat 114 to thereby supply the chamber 54with a pressure differing from that in the tube 22, which pressurethrough the tubular projection 60 will also be provided to the variablevolume chamber 66 to create pressure differentials across the walls 42and 44 and the associated diaphragms 32 and 34 to cause a displacementof the force transmitting or push rod 68 to the left as viewed in thefigure. At the same time, a pressure differential is created acrossdiaphragm 36 to create a reaction force opposing pedal force to allow alight finger spring 128 to hold the valve structure so long as pedalforce and reaction force are substantially equal.

If the travel of the movable walls 42 and 44 is approaching an excessiveamount, the springs 62 will start to bear upon the inwardly projectingportions of the spacer 24 to bring about a spring resistance to furthertravel. This is designed in the particular unit shown to occur at abouttwo-thirds of the maximum travel allowed for wall 42 so that at thetwo-thirds position, the springs will be generating 0 lb. of force, but,if the stroke is continued to approximately the three-quarters positionor maximum travel for wall 44, the springs will be exerting a 300-lb.force to the shell which would decrease the force available in rod 68 sothat pedal force must be increased to provide more differential to makeup for this loss.

In addition, the valve seat carrying member 86 is provided with aradially inwardly directed groove 126 for afiixing the annular springfinger mechanism 128 to member 86. The spring has depending portionsarranged so that when a great or excessive force is applied to the pedal96, the portions will rise over a cam 130 on a guide tube 132 to releasethe valve structure and permit followup manually to displace the pushrod 68. At this time, pedal force goes through member 94 to wall portion50 and thus to rod 68, bypassing the valve poppet rings and theappropriate seat means to prevent scarring the rings.

It will be apparent that the objects heretofore enumerated, as well asothers, have been accomplished and that there has been provided a newand improved servomotor.

While the invention has been described in considerable detail, we do notwish to be limited to the particular embodiments shown and described;and it is our intention to cover hereby all novel adaptations,modifications and arrangements thereof which come within the practice ofthose skilled in the art to which the invention relates.

We claim:

1. A fluid pressure servomotor comprising:

a housing;

a first movable wall in said housing;

a second movable wall in said housing;

an output means operatively connected to said first and second movablewalls;

a control mechanism operatively connected to said first and secondmovable walls for creating a similar pressure differential across thesame, which control mechanism is responsive to reactive forces from theoperation of said servomotor; and

means aflixed to one of said first movable wall or said second movablewall and normally inoperative until said one of said first and secondmovable walls has stroked a predetermined amount to engage said meanswith a portion of said housing to increase the reaction forces on saidcontrol means in accordance with the travel of said one of said firstand second movable walls in said housing.

2. A structure of claim 1 wherein said means is further characterized asa resilient means affixed to one of said first and second movable walls,which resilient means is adapted to transfer the power available fromsaid wall to said housing in increasing increments after said one ofsaid first and second movable walls has stroked a predetermined amountwithin said housing.

3. The structure of claim 2 wherein said servomotor further comprises aspacer means afiixed to said housing between said movable walls, saidspacer having a bearing surface for cooperation with said resilientmeans to incrementally transfer the power available from said one ofsaid first and second movable walls, as said wall ap proaches saidspacer.

4. The structure of claim 2 wherein said resilient means is a leafspring on said one of said first and second movable walls.

5. A fluid pressure servomotor comprising:

a movable wall means within a housing of the servomotor;

control means adapted to create a pressure differential for operatingsaid movable wall means, which control means has a link operativelyconnected to said movable wall means and to a manual control; and

resilient means affixed to said movable wall means and normally spacedfrom an end wall of said housing and engageable therewith to be therebyoperative to indicate the approach of stroke run-out condition of saidmovable wall means as it approaches said end wall of said housing byincreasing reaction forces on said link and said manual control inaccordance with the stroke of said movable wall means above apredetermined travel.

6. A fluid pressure servomotor according to claim 5 wherein said controlmeans comprises a balanced valve means controlling the operation of themovable wall means within the servomotor, which balanced valve means isprovided with releasable holding means operatively connecting said valvemeans to the servomotor and arranged to release said valve means toallow follow-up movement of the valve means without damage of said valvemeans during the application of excessive pressure to translate saidmovable wall means.

7. A fluid pressure servomotor according to claim 5 and furthercomprising a force transmitting rod operatively connected to saidmovable wall means and to a return spring operatively connected betweenthe servomotor and the movable wall means so as to maintain the movablewall means to the rear of the servomotor in the released attitude, saidrod having a return stop means operatively connected to the servomotorto limit its inward position in said servomotor.

8. A fluid pressure servomotor according to claim 7 wherein said movablewall means includes first and second movable walls and said rod forms aninner support and guide for said second movable wall and a spacer meansthat is arranged between the first and second movable walls and isprovided with an annular opening to which sealing means is operativelyconnected to support and guide said first movable wall within saidservomotor.

9. A fluid pressure servomotor comprising:

a housing including two shell portions sealing-1y joined with a spacerbody dividing a chamber internally thereof into' two portions;

a first movable wall operatively arranged in said housing behind saidspacer in one portion of said chamber;

a second movable wall operatively arranged in said housing ahead of saidspacer in the other portion of said chamber;

a force transmitting means which is operatively connected to said firstand second movable walls and relatively movable with respect to at leastone of said first and second movable walls;

a control mechanism operatively associated with said servomotor withinsaid housing to control said first and second movable walls, whichcontrol mechanism is operatively associated with said force transmittingmeans to manually actuate same in the absence of actuation thereof bysaid first or second movable walls;

means to position said force transmitting means in a released position,which means is operatively connected to said first and second movablewalls; and

a member operatively connected to one of said first and second movablewalls, which member is normally inoperative until one of said first andsecond movable Walls is stroked a predetermined distance within saidhousing and thereafter operative to reduce the eflectiveness of said oneof said first and second movable walls whereby reaction forces will berapidly increased on said control mechanism to indicate an abnormalcondition occurring in said servomotors such as excessive travel of saidfirst and/or second movable walls.

10. A fluid pressure servomotor according to claim 9 wherein saidcontrol mechanism includes a valve means and releasable holding meansfor said valve means arranged to release said valve means upon manualactuation of said force transmitting means.

11. A fluid pressure servomotor according to claim 10 wherein said valvemeans is characterized as balanced valve means.

12. A fluid pressure servomotor according to claim 11 wherein saidspring is located on said first movable wall to be normally spaced fromsaid spacer and to contact said spacer upon an excessive stroking ofsaid first movable wall to reduce the efliectiveness of said firstmovable wall on said force transmitting means whereby reactive force onsaid control mechanism will be rapidly increased thereafter.

13. A fluid pressure servomotor according to claim 9 wherein saidcontrol mechanism is mounted to said housing by a third movable walllocated behind said first movable wall such that control pressurescheduled by said valve means to stroke said first and second movablewall also reacts to hold valve travel to a minimum.

14. A fluid pressure servomotor according to claim 9 wherein said memberis further characterized as a spring aflixed to one of said first andsecond movable walls, which spring is adapted to transfer the poweravailable from said wall to which it is affixed to said housing inincreasing increments after said one of said first and second movablewalls has stroked a predetermined amount within said housing.

15. A fluid pressure servomotor according to claim 14 wherein said valvemeans is further characterized as balanced valve means.

16. A fluid pressure servomotor comprising:

a first movable wall;

a second movable wall connected to said first movable wall;

a spacer means rigidly affixed between said movable walls; and

valve means controlling the operation of said movable walls within theservomotor, which valve means is provided with operator-operated meansand with a releasable holding means operatively connecting said valvemeans to the servomotor, said holding means being operatively connectedto said operator-operated means to allow follow-up movement of the valvemeans without damage of said valve means during the application ofexcessive pressure to said operator-operated means to translate saidfirst and second movable walls.

17. A fluid pressure servomotor comprising:

a first movable wall;

a second movable wall operatively connected to said first movable wall;

a spacer means rigidly affixed to said servomotor between said first andsecond movable walls;

a force transmitting means slidably carried by said spacer means andoperatively connected to said first movable wall and said second movablewall for actuation thereby;

a valve means for controlling the translation of said first and secondmovable walls which valve means is provided with an operator-operatedmeans and with a releasable holding means arranged to release said valvemeans in accordance with the force applied to said operator-operatedmeans to allow said valve means to manually actuate said forcetransmitting means; and

pressure responsive means to mount said valve means within theservomotor.

18. A fluid pressure servomotor comprising:

a first movable wall;

a second movable wall operatively connected to said first movable wall;

a spacer means rigidly aflixed in said servomotor between said first andsecond movable walls; and

a balanced valve means controlling the operation of the movable wallwithin the servomotor, which balanced valve means is provided with anoperator-operated means and a releasable holding means operativelyconnecting said valve means to the servomotor said holding means beingoperatively connected to said operator-operated means to allow follow-upmovement of the valve means without damage of said valve means duringthe application of excessive pressure to said operator-operated means totranslate said first and second movable walls, said valve means beingresiliently biased to oppose forces on said operator-operated meanswithin the servomotor.

References Cited UNITED Almond 92-48 Schultz 91-376 Mallory 92-23 Ayerset a1. 91-391 Pi'ather 91-434 Ayers 92-49 Hcmrneter 92-23 MARTIN P.SCHWADRON, Primary Examiner.

PAUL E. MASLOUSKY, Examiner.

